Views have three different Privacy settings: Public, Private, and Public Read Only.
Public views can be viewed by any user that has access to the object.
Private views can only be viewed by:
The user who created the view
System administrators
Any users that were selected to share the view
Public Read-Only views are just like Private views except that they cannot be modified by anyone other than the user who created it, or a system administrator. You can save data.
You have two options to set the privacy of a view:
Click the drop-down arrow next to Save and click Save View. The Save View / Save View As screen appears. Click the Privacy drop-down menu and select the desired option.
Click the drop-down arrow next to Configure and click Manage Views. The Manage Views screen shows all of the existing views. Modify the Privacy field as needed, then click Save.
To update the privacy of multiple views simultaneously (especially if you have a large number of views), consider using the Mass Update action. Select the views to update in the Manage Views screen. Click Actions (in the Manage Views screen) and select Batch Edit > Mass Update. Then update the privacy for the views.